Effect of solute–solvent interactions on DPPH radical scavenging efficiency of some flavonoid antioxidants in various binary water–methanol mixtures

Abstract

Scavenging ability of three kinds of natural flavonoid antioxidants including chrysin, naringenin, and quercetin against the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical was evaluated by the UV-vis spectrophotometric technique in different aqueous mixtures of methanol (50%–90% v/v) at physiological pH. The studied flavonoids showed their activity to be comparable with ascorbic acid (vitamin C), which is used as a standard reference material in most testing methods. Our findings indicated that an increase in the organic solvent percentage (v/v) has different effects on the radical scavenging efficiency of flavonoids presumably due to solute–solvent interactions. These variations were analyzed in light of various simple and multiple regression equations using the normalized polarity parameter ([Formula: see text]) and Kamlet, Abboud, and Taft solvatochromic parameters. Moreover, The IC50 values of the samples were then obtained by the Yasuda–Shedlovsky extrapolation procedure in pure water.